Such a coating plant is known from EP 1 287 900 A2 and from “Technical Manual for Paint Volume Control”, page 32 (1994) from the Dürr Company in which a rotary atomizer is supplied with the coating means to be applied through a paint pressure regulator and a metering pump. The pressure of the coating means ahead of and behind the metering pump is measured by pressure sensors and sent to electronic controls which actuate the paint pressure regulator through a pressure control valve configured as a proportional valve. In the case of this known coating plant, either the output pressure of the paint pressure regulator or the paint flow rate is regulated as the control variable.
The disadvantage of the previously described known coating plant-bis the wear on the metering pump and the paint pressure regulator, which results in a short service life for these components. This applies in particular to the paint pressure regulator, the seal ring of which exhibits extremely severe erosion after a certain operating time.
In addition, with the conventional coating plants, inaccuracies in metering may occur which, in an extreme case, result in cessation of the paint flow which shows up as a paint defect on the parts to be coated.